Method of treating materials containing sulphur



PatentedFeb.7,1939 r 2,146,294

umreo STATES PATEN OFF-ICE:

p t I i a IMETnonoFJTREATING MAT RIALSooN it TTAINING SULPHUR. CarleR ljia y ward,

Nom wmg. ap lication October 7, 1936, 1

Serial No. 104,503

, t T2 Claims. (01. 75-77) r This invention relates to a'metliod of treatingfi dustrial quantities may be"econoinically accomrnetallic by-DroductSfor waste materials contain- 'plished. Y i f ing sulphur; such'as leadbattery plates; roasted More particularly, it is now'found that water i or {sintered -lead concentrates, dresses and like solutionsof the alkali metal hydroxides; or weak 5 materials lin which the lead exists in wholeor alkaline salts of the alkali metalslsuch jas caustic 5 inpartassulphate. l soda and sodium carbonatel'fwhedapplied to In the usual methods of smelting andrecov- :-masses of materials containing insoluble sulering lead products, the presence of sulphurphatesfsuch as lead sulphate, are reactive with causes the formation of matte or drosswhich rethe sulphate radical to form the corresponding quires reworking. This involves additional exalkali metal sulphate. The latter dissolves in 10 V 1 penseofoperations and usually some loss of the the solution (or water) and leaves a heavy melead content. The presenceof sulphur also neces tallic residueor reaction product Which is in a, sitates carrying out such operations at higher porous condition, such that succes Portions temperatures than would be required if all the of the alkaline solutionmay penetrate linto and lead were present a oxide, throughthe sulphate mass, removing the sul- 15 It is accordingly an object of this invention to D and leaving a D H maSSOf'thB eac on provide a'method for the moreconvenientjecop od f l suehas he rbona e an r nomical and effective recoveryloflead or'of lead Oxide. l l l products from waste materials containing lead, ep mass as thus formed y b ore e and particularly .fromthose which contain more mp etely Separated from the soluble or .dis- .20 or less lead sulphate lor sulphate-bearing comsolved sulphate by sh g n water. It is then pounds t is alsoan object to provide amethod in a condition substantially free from sulphate which shall be adaptable to the practices and n S p d in whichlt y be ad y equipment m nl employed in the art f res'melted and reduced to the condition of free j covering lead. Other objects will appear from m al o developed to h ot er rm s, may 25 r the following disclosure. f r l be edo example, the completely de- In accordance with. this invention, it .is found p a e mass l With a r n that sulphate-bearing materials, in which the, agentwith or without the addition of fluxes, .to

. sulphate is insubstantially water-insoluble form, du and recover e lead- Other du ibl such as lead sulphate, the sulphur'content may o po Whichmay berpresenli in e c arge, 30 nevertheless be removed by convertingthe sulsuch as antimony, may-alsobe recovered at the :phate component into a water-soluble form and Same time, y p p ate treatment in the usual then dissolving and leaching it from the residual y l mass of material withywhich it has been asso- In this connection, the flux compositionstand elated. If a partior all ofv the sulphuris present methods of procedure described my United v35 as sulphide, as in c oncentratesfromsulphide lead States Patent 1304054 may advantageores, it may be firstoxidized 'tothe insoluble sul- S Y e p ye When operating upon scrap phate, preliminary to the conversion to soluble attery p a in this manner pe atures 01' sulphate. It is found that such conversion of 700 to 800 C. havebeen satisfactorily employ 0 the insolublesulphate to soluble sulphate, tohigh recoveries. of lead and antimony havetbee do gether with dissolution of thesoluble sulphate effected, d b t little dross-or fumeis enthus formed, leaves the surface or the residual countered.

a .lead orlead-containing material which has been In a typic mp e e practical applicathusreacted upon ln'an open, porous condition. tion of my io Se apbattery plates may Therefore, further penetration of the mass by be used, which have been sulphated so as to 45 the converting reagent may bereadily effected contain a considerable deposit or formation of so as to permit its further reaction upon the inlead sulphate, and a, high recovery yield of the soluble sulphate, and the soluble sulphate thus lead content has been obtained. g \for'med may be readily dissolved and removed. Thus a pile of the scrap battery plates maybe Inthis way the conversion and dissolution of leached with the reagent solution or the charge the sulphur-bearing component of the material may be immersed in thealkaline solution ina isprogressive throughout the mass or lumps, etc. suitable tank. The solution is conveniently made of material under treatment, is easily effected, up with normal sodium carbonate orsoda ash, andsubstantially complete conversion of large ineither dilute or concentrated but preferably at or approximating saturation at atmospheric temperature.

The reagent solution may be passed over and through the mass by suitable circulation, as by pumping, or the charge may be left submerged for a sumcient time to permit complete penetration and conversion of the insoluble sulphate to soluble sulphate form by the progressive penetration and conversion of the sulphate components oi the mass or charge as a whole. The time required will depend upon the size, composition and physical characteristics of the material under treatment. But it may be determined and controlled, by removing the initial reagent solution, washing until the wash waters are substantially free from soluble sulphate, treating with iresh alkali solution and then testing this for sulphates. When no further tests for sulphates are obtained the charge may be considered as free from its sulphur content.

A suitable, rapid, and in some respects more convenient procedure, is to subject a succession of charges or a continuous stream of the material containing insoluble sulphate to a counter-current oi the alkali reagent solution, which may be readily eflected in known ways.

The resulting impregnated, converted and leached product thus obtained contains substantially no sulphur as sulphate, but is made up primarily of tree metallic lead, lead oxides, salts and boric salts or hydrates of lead which may be readily reduced to the tree metal in known ways. It is of an open porous texture, and in a condition suitable for reconversion and reuse in any of the many forms in which lead and lead compounds are commercially desired or required, in highly satisfactory condition.

I claim:

1. A method of treating roasted or sintered sulphide lead ore concentrates, in massive or lump condition, which comprises subjecting the same directly and without mechanical crushing or grinding to an alkaline aqueous solution of an alkali metal compound to form soluble sulphate, removing said soluble sulphate, and smelting the residue thus obtained under reducing conditions.

2. A method oi treating materials composed substantially of water-insoluble metal sulphate, in massive or lump condition, which comprises subjecting the same directly and without mechanical crushing or grinding to an alkaline aqueous solution of an alkali metal compound to form soluble sulphate, removing said soluble sulphate, and smelting the residue thus obtained together with a flux under reducing conditions.

CABLE R. HAYWARD. 

